Abstract
BACKGROUND: The aim of this study was to investigate the influence of marking methods on the outcomes of body composition analysis and provide guidance for the selection of marking methods in mouse body composition analysis. METHODS: Male C57BL/6J mice aged 6 weeks were randomly assigned for pre- and post- ear tagging measurements. The body composition of the mice was measured using a small animal body composition analyzer, which provided measurements of the mass of fat, lean, and free fluid. Then, the mass of fat, lean and free fluid to body weight ratio was gained. Further data analysis was conducted to obtain the range and coefficient of variation in body composition measurements for each mouse. The distribution of fat and lean tissue in the mice was also analyzed by comparing the fat-to-lean ratio. RESULTS: (1) The mass of all body composition components in the ear tagging group was significantly lower than that in the control group. (2) There was a significant increase in the range and coefficient of variation of body composition measurements between the ear tagging group and the control group. (3) The fat-to-lean ratio in the ear tagging group was significantly lower than that in the control group. CONCLUSIONS: Ear tagging significantly lowered the results of body composition analysis in mice and higher the results of measurement error. Therefore, ear tagging should be avoided as much as possible when conducting body composition analysis experiments in mice.